1 files changed, 56 insertions, 0 deletions
diff --git a/lib/libm/ctanf.c b/lib/libm/ctanf.c
new file mode 100644
index 00000000..fe117d7a
--- /dev/null
+++ b/lib/libm/ctanf.c
@@ -0,0 +1,56 @@
+#include "__complex.h"
+
+static float _ctansf(float complex z)
+{
+	float f, x, x2, y, y2, rn, t, d;
+
+	x = fabsf(2.0f * crealf(z));
+	y = fabsf(2.0f * cimagf(z));
+	x = redupif(x);
+	x = x * x;
+	y = y * y;
+
+	x2 = 1.0f;
+	y2 = 1.0f;
+	f = 1.0f;
+	rn = 0.0f;
+	d = 0.0f;
+
+	do {
+		rn += 1.0f;
+		f *= rn;
+		rn += 1.0f;
+		f *= rn;
+		x2 *= x;
+		y2 *= y;
+		t = y2 + x2;
+		t /= f;
+		d += t;
+
+		rn += 1.0f;
+		f *= rn;
+		rn += 1.0f;
+		f *= rn;
+		x2 *= x;
+		y2 *= y;
+		t = y2 - x2;
+		t /= f;
+		d += t;
+	} while (fabsf(t / d) > MACHEPF);
+
+	return d;
+}
+
+float complex ctanf(float complex z)
+{
+	float f = cosf(2.0f * crealf(z)) + coshf(2.0f * cimagf(z));
+
+	if (fabsf(f) < 0.25f)
+		f = _ctansf(z);
+
+	if (f == 0.0f) {
+		return HUGE_VALF + HUGE_VALF * I;
+	}
+
+	return sinf(2.0f * crealf(z)) / f + (sinhf(2.0f * cimagf(z)) / f) * I;
+}